Solvent recovering and purifying method and apparatus



Dec. 25, 1962 D. J. BARDAY 3,070,463

SOLVENT RECOVERING AND PURIFYING METHOD AND APPARATUS Filed June 8, 1961 2 Sheets-Sheet 1 INVENT OR DOnQZdJBCwd g ATTORNEYS n. J. BARDAY 3,070,463

Dec. 25, 1962 SOLVENT RECOVERING AND PURIFYING METHOD AND APPARATUS Filed June 8, 1961 2 Sheets-Sheet 2 I (IllIIIIIIIIIIII'IIIII'II'I INV ENT OR 1 DonaZdJBamZgy wad/$ ATTORNEYS m I. l -|v. fi fl E m an m w m w A v T: 0 m Hp m m J m United States Patent F 3,076,463 SOLVENT RECOVERING AND PURIFYING METHOD AND APPARATUS Donald J. Barday, Greentree Drive, West Chester, Pa. Filed June 8, 1961, Ser. No. 115,635 21 Claims. (Cl. 134-11) economical to tolerate the normal losses occurring in dry cleaning from vapor losses and solvent contamination.

Such fluorinated hydrocarbon solvents are trichloromonofluoromethane, trichlorotrifiuoroethane and tetrachlorodifluoroethane.

An object of this invention is to provide a means for minimizing solvent losses in a dry cleaning machine.

Another object is to provide a simple and economical means for recovering cleaning solvent from the vapor space of a dry cleaning machnie.

Still another object is to provide a simple and economical method of purifying contaminated solvents; and

A further object is to provide a simple and economical means of simultaneously recovering and purifying solvent in a dry cleaning machine.

In accordance with this invention solvent is recovered from the vapor space of a dry cleaning machine by abstracting and cooling the machines air and vapor mixture to condense part of its solvent contact and collect and reuse accordingly distilled solvent. The uncondensed air and vapor is then heated to regenerate its solvent absorbing ability and conserved by returning it to the drying chamber of the cleaning machine where it is used to facilitate drying. The aforementioned vapor abstracting and condensing operations also minimize pressure build-up within the vapor space of the machine.

These vapor condensing and heating steps can be remarkably economically performed by the heat absorbing and emitting sections of a heat pump. Solvent condensing and evaporating chambers enclose these sections and are connected in a closed circuit in series with each other and with the vapor space of the dry cleaning ma chine. This permits an air and vapor mixture to be continuously withdrawn and part of the vapor condensed from the mixture. The uncondensed mixture is heated and returned to the vapor space to restore its solvent absorbing ability which permits it to help dry clean items. The condensate may be used to replenish a clean rinse solvent storage tank; and, therefore, simultaneously purify the solvent as it is being recovered. I

In a continuously operating machine where cleaned items are continuously discharged through an exit from the vapor space, the heated air and vapor mixture may be directed into the exit in counter-current how to the exit ing items to minimize the amount of vapor flowing out of the exit with them as the vapor is reintroduced into the system. In a closed chamber intermittent cycle type of machine part of the solvent used for washing can be sprayed into the solvent heating or evaporating chamber and then condensed to purify enough clean solvent to make up what is used during each cycle of operation. Both ends of a heat pump cycle can also be remarkably effectively and economically employed in such a system as well as in an independent solvent purifying system.

Novel features and advantages of the present invention will become apparent to one skilled in the art from a reading of the following description in conjunction with 3,070,463 Patented Dec. 25, 1962 the accompanying drawings wherein similar reference characters refer to similar parts and in which: FIG. 1 is a schematic diagram of a solvent purifying embodiment of this invention;

FIG. 2 is a schematic diagram of a continuously operating dry cleaning machine which incorporates aspects of this invention;

FIG. 3 is a schematic diagram of another type of con-" tinuously operating machine utilizing additional aspects of this invention; and

FIG. 4 is a schematic diagram of an intermittently X operating closed type of dry cleaning machine utilizing still another aspect of this invention.

In FIG. 1 is shown a system 10 for purifying dirty solvent contained in a tank 12 and accumulating it in clean solvent tank 14. The solvent being purified may be of any type used in dry cleaning;v and, for example, may be one of the more expensive solvents such as trichlorotrifiuoroethane.

As shown in FIG. 1, a pump 16 draws dirty solventand heat emitting section 30 is, for example, the re frigerant evaporating coil.

Heat absorbing element 30 is enclosed within a solvent condensing chamber 38, and a' vapor conduit 40 connects solvent condensing chamber 38 with solvent evaporating chamber 20 to permit the vapor in solvent evaporating chamber 20 to be conducted to solvent condensing chamber 38.

A lower point of solvent evaporating chamber 20 is' connected to contaminated solvent tank 12 by a drain line 42, and a lower point of solvent condensing chamber 38 is connected to clean solvent storage tank 14 by drain line 44.

Apparatus 10 shown in FIG. 1 operatesin a remark-' ably efiicient and economical manner by virtue of its use of both ends of heat pumping system 26. Pump 16 discharges dirty solvent through spray line 22, which may include a set of nozzles (not shown), over heat emitting coils 24 of heat pumping system 26. The heat in coils" 24 evaporates a considerable amount of the solvent from which an appreciable amount of foreign matter has already been removed by filter 18. The unev'aporated sol-' by other methods.

vent returns to tank 12 through drain line 42, which also returns dissolved liquids, such as oil and other relatively nonvolatile liquids, which do not evaporate in the solvent evaporator, to the contaminated solvent tank for removal The evaporated solvent is directed through conduit 40 into solvent condensing chamber 38 where it is cooled and condensed by heat absorbing coils 30. The condensed clean solvent is then directed into clean solvent storage tank 14 through drain line 44.

This system is remarkably efiicient because all of the energy made available by heat pumping system 28 is utilized; and the evaporation process occurs at a relatively lower temperature than the normal boiling point of the solution at atmospheric pressure. This minimizes the carry over of droplets of foreign matter in the vapor into the solvent condensate in comparison to evaporations conducted at higher temperatures and higher kinetic energy levels. In addition, system 10 shown in FIG. 1 is remarkably compact and trouble free in operation.

In FIG. 2 is-shown a continuously-operating dry clean ing system or apparatus 50 including a casing 52 having an entrance tube 54 and an exit tube 56. Dirty items such as a strip of photographic film 58 are introduced into chamber 52 through entrance 54 and discharged through exit 56 after being dry cleaned within casing 52. Film 58 is, for example, automatically drawn through casing 52 by a winding roller (not shown) and directed over a series of guide rollers 60 in its passage through casing 52.

' Casing 52 is divided by a bulkhead 62 into a washing chamber 64 and a drying chamber 66. The bottom 68 of casing 52 forms a tank for storing a supply of washing solvent 70, which is of a relatively contaminated nature because dirty film 58 is first passed through washing solvent 70 and thereby relieved of most of its foreign matter. A rinse tank 72 is also mounted with the casing 52 with its top disposed above the level of washing solvent 70. Tank 72, therefore, can overflow through upper drain pipe 74 into washing solvent 70 and actually does so in a manner later described in detail.

After film 58 passes through washing solvent 70 and relatively cleaner rinse solvent 76 in tank 72 it passes through connecting tube 78 into drying chamber 66 where practically all of the solvent is evaporated from it to permit clean film 58 to pass out of casing 52 through exit 56. The solvent recovering and purifying portions of the apparatus are now described.

The cleaning solvent utilized in this machine may be relatively expensive, and it is therefore desirable to provide simple and economical means of recovering and purifying solvent within casing 52 and preventing it from passing out into the surrounding'atmosphere with the cleaned items. To accomplish this, part of the air and solvent vapor mixture within the vapor spaces of casing 52 are abstracted through conduit 80 and circulated through a vapor condensing chamber 82 which includes a heat absorbing element 84 of a heat pumping system 86. A series of baffles 88 lengthen the path of contact of the vapor over heat absorbing coils 84.

"Heat pumping system 86 includes a refrigerant compressor 90, a refrigerant heat rejecting section or refrigerant condenser 92 cooled by fan 94. An expansion valve 96 controls the evaporation of refrigerant within the heat absorbing coil 84, and the parts of heat pumping system 86 are connected by piping 98.

A vapor conduit 160 connects refrigerant evaporating chamber 82 with casing exit 56, and blower 102 propels vapor from chamber 82 into exit 56. At the same time the solvent condensate at the bottom of chamber 82 is directed into rinse tank 72 through drain line 104 which provides a remarkably convenient manner of continuously purifying the solvent in the system as it is being recovered. The greater surface area of washing solvent 70 in casing 52 provides the primary source of solvent vapor in the vapor spaces of casing 52, which provides a remarkably convenient means of continuously puriying the relatively dirty washing solvent. At the same time a supply of relatively clean rinse solvent 76 is replenished in rinse tank 72.

Before the vapor in conduit 100 is discharged into casing 52, it is raised in temperature by heater 106, which is for example an electric heater to restore its solvent vapor-absorbing ability. Furthermore, heated vapor is discharged in counter current relationship to the path of cleaned film 58 through exit 56 by directing its flow inwardly through inwardly directed passageway 108 at the bottom of exit tube 56. This heated vapor is ca pable of absorbing solvent drying from cleaned film 58 through drying chamber 66, and it is directed by bafiie 110 to pass through drying chamber 66 substantially in the direction of arrows 112. From drying chamber 66 arrows 112 indicate the passage of heated solvent vapor through connecting conduit 78 into washing chamber 64 through which baffie 114 directs it first down and then allows it to pass upwardly. through vapor extracting tube into vapor condensing chamber 82. The continuous abstraction of vapor from vapor spaces 64 and 66 into condensing chamber 82 minimizes the vapor pressure in the machine and automatically cleans and recovers solvent vapor in the machine atmosphere. Operation of the heat pump system 86 during shut down periods also insures that the vapor pressure within the machine is therein minimized, which also accordingly minimizes solvent losses.

In FIG. 3 is shown a system which is a modification of system 50 shown in FIG. 2, which also utilizes a heat pumping system 26A similar to that shown in FIG. 1 for evaporating and condensing solvent vapor. Parts shown in FIG. 3 identical or highly similar to those in FIGS. 1 and 2, are designated by similar reference characters and are not herein again described. In this connection the path of items being cleaned are merely indicated by arrows 58A.

However, a pump 122 is utilized for pumping solvent condensed from lower refrigerant condensing chamber 82A into rinse tank 72A, and both heat emitting coils 24A and an electric heater 106A are provided for heating the solvent vapor to be returned through exit 56A into casing 52A. In most instances only the heat emitting element 24A is sufiicient to maintain vapor temperatures. However, should additional heat be needed it can be added by electric heater 106A. System 120 in FIG. 3 therefore provides a remarkably compact and efiicient manner for utilizing a simple heat pumping system 26A for both recovering and purifying solvent vapor within a dry cleaning machine.

In FIG. 4 is shown a closed intermittently operating dry cleaning machine or system 130, which utilizes many of the aforementioned features and where such features are similar to those previously discussed they are designated by similar numbers followed by the letter B and largely not redescribed. In this connection system includes a heat pumping system 26B with inter-connected solvent condensing and solvent evaporating and heating chambers 38B and 2013. In this closed intermittently operated machine, items to be cleaned such as clothing are introduced into casing 52B through an inlet door 132. Wash solvent is stored in a contaminated solvent container 12B, and relatively cleaner rinse solvent is stored in clean solvent tank 14B. A description of the cycle of operation of apparatus 130 facilitates an understanding of the various parts that it incorporates.

Contaminated solvent is withdrawn from wash tank 12B through filter 18B, valve 134 and pump 135 and discharged into casing 523 for performing the washing portion of the cycle. This contaminated washing solvent is later withdrawn from casing 52B through drain line 136, detergent decanter 138 and valve 1408 back into wash solvent container 12B.

During the wash and rinse cycles, part of the contaminated solvent in tank 128 is purified by pumping it by pump 16B through valve 140 and spray line 22B over heat emitting coils 24B in solvent evaporating chamber 20B. The unevaporated solvent in chamber 208 is returned to wash solvent container 12B through drain line 42B and valve 142. The solvent evaporated in chamber 20B is conducted through conduit 40B into solvent condensing chamber 38B, in which part of it is cooled by heat absorbing coils 30B and directed through drain line 44B into clean rinse tank 14B. Sufiicient solvent is purified during the wash and rinse cycles to make up a quantity of solvent sufficient for rinse purposes.

Purification of part of the solvent vapor in casing 528 is accomplished during a portion of the cycle by drawing it down through orifice or inlet tube 148 in the top of inverted U-shaped tube 144 into chamber 38B when its lower end 146 is immersed in solvent within casing 52B. Part of the solvent is therein condensed, and this purified condensate is returned to rinse the tank 14B. This constitutes a relatively small quantity of purified liquid, and

its condensation serves primarily to avoid pressure build up in enclosure 52B. During the drying portion of the cycle, the uncondensed vapor and air mixture is conducted into solvent evaporating and heating chamber 20B by blower 10213 through vapor conduit 4033, where it is heated and returned through vapor return conduit 106B into casing 52B. The complete cycle of operation of intermittently operated closed machine is now described in detail.

Operation of FIG. 4

Apparatus 130 shown in FIG. 4 operates in accordance with the following cycle which is coordinated by a motor-operated timer of the type which is for example used for controlling the cycle of an automatic clothes washing machine. Apparatus 130 also, for example, incorporates other unillustrated parts of a conventional dry cleaning machine, such as a tumbling drum. The first timed operation is that of main pump 135 which fills machine casing 52B if vapor-tight inlet door 132 is closed.

Pump 135 draws its supply from tank 123 through filter 18B and automatic valve 134 which in addition to the other automatic valves in this apparatus is, for example, solenoid-operated. At the same time a predetermined quantity of detergent solution is admitted to cleaning machine chamber 52B from detergent container 150 through detergent metering valve 152.

Purifying pump 16B starts approximately at the same time as main pump 135 and begins circulating cleaning fluid solvent through valve 140 and pipe 154 into solvent evaporating chamber 20B. At this same time drain valve 142 from chamber 20B opens to return unevaporated dirty solvent to tank 12B through drain pipe 423. Before heat emitting element 24B comes up to operating temperature, practically all of the solvent circulated by purifying pump 16B is accordingly returned to washing solvent container 128. Heat pumping system 26B then starts to operate after a short delay to bring heat emitting coils 24B up to operating temperature which then start to evaporate a fraction of the solvent liquid sprayed over them through pipe 22B. The evolved vapor passes through conduit 40B over heat absorbing coils 30B which extract the latent heat of condensation causing the vapor to condense or liquify. Orifice tube 148 at the top of inverted U-shaped tube 144 relieves pressure from chamber 38B into machine chamber 52B to prevent pressure build-up within chambers 20B and 38B. The purified solvent is directed to and stored in rinse tank 14B through vapor condensing chamber drain tube 44B and pure solvent return valve 156 which is maintained open as long as heat pump 26B is operated at rated output.

As the level of solvent washing liquid rises in machine chamber 5213 the entrance to the lower leg 146 of inverted U-shaped tube 144 is blocked which causes vapor within chamber 52B to be conducted through inlet tube 148 in the top of U-shaped tube 144 down into solvent condensing chamber 38B where it is condensed to liquid in a similar manner to that previously described. When the solvent level in chamber 52B rises to the washing level, main pump 135 stops and its suction valve 134 closes. However, purifying pump 16B may run for example during the entire wash, extraction rinse and subsequent extraction processes to permit enough solvent to be purified to replenish the amount of rinse solvent abstracted from rinse tank 14B during a cycle of operation.

At the end of the washing cycle drain valve 140B opens to return used solvent to tank 12B while detergent is decanted and drawn oif in detergent separator 138. Drain valve 140 remains open during the extraction and spin dry cycles following the wash cycle.

However, drain valve 140B closes after the first extraction cycle, and rinse tank valve 158 then opens to admit cleaning solvent to main pump 135, which is then started and run to fill chamber 52b to the operating level with clean rinse solvent after which main pump 135 is again stopped.

' Drain valve 140B is then opened at the end of the rinse cycle to return the now contaminated rinse liquid to tank 12B. Up to this time the combined evaporating and condensing processes accomplished in solvent evaporating and condensing chambers 20B "and 38B are, for example, sufiicient to produce enough purified solvent to fill chamber 528 to its operating level with clean rinse liquid stored in solvent tank 14B. After one usage in the machine, this liquid is subsequently used in the wash cycle.

Drain valve 140B remains open until the extraction step following the rinse cycle is completed when it closes. The clothing in the machine is then tumbled by rotation of the drum (not shown) to dry the clothing. At the beginning of this drying process, blower 102B starts to operate and purifying pump 16B stops with valves 140 and 142 also closing. The pressure created by blower 102B forces the air and vapor mixture through inverted U-shaped tube 144 into condensing chamber 383 which condenses a substantial amount thereof and returns it to clean solvent storage tank 14B. Any uncondensed vapor and air in chamber 38B then flows through conduit 403 into solvent evaporating and heating chamber 20B where it is heated to restore its solvent absorbing ability by decreasing its relative humidity. This relatively dry air and vapor mixture is then returned to washing machine chamber 523 through conduit B and blower 1023 where it helps abstract solvent from the atmosphere in chamber 523 to dry items such as clothing being tumbled therein. Since the air and vapor cycle is completely closed almost none of the solvent in the vapor is lost to atmosphere, and substantially all of the solvent is condensed and returned to the form of clean solvent to storage container or tank 14B.

When the drying cycle is completed, blower 102B and compressor 28B of heat pump 26B are stopped and rinse return valve 156 is also closed to isolate the solvent stored in tanks 14B and 12B preventing any loss through evaporation. The entire system is now ready for another wash cycle.

The time increments for each portion of the aforementioned cycle can be adjusted to provide optimum washing, drying and extracting conditions and to purify enough solvent and store it in tank MB to fill the machine tank for the next cycle. A complete cycle may be accomplished in approximately as little as one-half hour. As previously described, some solvent is purified by auxiliary evaporation by spraying it over heat emitting coils in evaporating chamber 20B, and some solvent is purified by condensation from the vapor atmosphere in chamber 52B. Nevertheless, some minor loss solvent is inevitable, and the proper level is maintained by adding small amounts of solvent.

The normal heat pump rejects more heat than it can absorb. A small auxiliary refrigerant condenser which is cooled in the ambient atmosphere is, therefore, probably necessary to maintain the proper heat balance between heat rejected and absorbed during the drying cycle. Transient conditions will also occur in which the machine and clothing surrender heat which facilitate the evaporation of solvent while reducing the temperature of the drying items and machine parts. This heat will, however, be restored near the end of the drying cycle when the heated mixture of air and vapor pass through blower 102B to rewarm both the machine parts and clothing. During the intermediate drying part of the cycle, approximately adiabatic conditions will develop in which the total heat content remains approximately at equilibrium. Furthermore, most of the free vapor in the machine at the beginning of the drying cycle is condensed in heat absorbing chamber 3813. During the drying cycle, a temperature in solvent condenser 38B of approximately 20 F. to 30 F. will provide efiicient solvent condensation; but purification can 'be accomplished at relatively higher temperatures such as approximately 40 F. The rate of air and vapor circulated may also be adjusted to provide optimum operating conditions.

When for example heat absorbing chamber 38B is operated with the surfaceof heat absorbing element 30B at 35 F., the mixture of air and vapor traversing chamber 38B is reduced to approximately F., and heating chamber B may correspondingly be operated at 110 F. to warm the air and vapor going through it to 80 F. During the drying cycle, the air and vapor mixture in chamber 52B may'begin at a wet bulb temperature which remains substantially constant at 23 R, which is governed by the conditions in chambers 20B and 36B. However, the dry bulb temperature decreases during the drying cycle while the. relative and absolute humidity increase, which is caused by the evaporation of solvent from the clothing. The relative humidity of the air passing through the machine accordingly increases in a range of 100% to 50% and perhaps lower. Actually the relative humidity of the atmosphere within chamber 523 approaches 100% at the start of the drying cycle and gradually decreases to approximately 50%. Even so, rapid drying will be accomplished with air leaving chamber 52B at approximately 50% relative humidity.

The apparatus and method of this invention therefore provide the following advantages. The solvent is substantially fully recovered as well as purified, and any pressure build-up in the machine is prevented. The purification can be accomplished either directly from condensation of vapor in the vapor space or by auxiliary evaporation and condensation by contact with heat emitting and absorbing sections of a heat pump. During the drying cycle, solvent may be condensed from the air and vapor mixture at a temperature of approximately 0 F. at a relative humidity of 100%. By contact with the heat emitting element of the heat pump the mixture is raised to a temperature of 80 F. at relative humidity which permits it once more to absorb solvent from clothing being dried. Operation under these conditions permits. an eight pound load of clothing to be dried in ap proximately three minutes with the recovery of approximately five pounds of clean solvent. The abstracting and condensation of solvent from the vapor space of the machine, also prevents any pressure buildup within the entire cleaning cycle. An auxiliary purification cycle may evolve and condense vapor at approximately five and one-half pounds per minute which is suflicient to replenish the solvent supply necessary for rinsing.

In a continuous flow type of cleaning machine, such as that described in FIGS. 2 and 3 for cleaning metal and plastic parts, conducted through the machine by a conveyor of any type or photographic film or magnetic tape reeled through it, the solvent purification is performed concurrently with washing and rinsing, which makes. it unnecessary to resort to any auxiliary solvent purifying processes. Furthermore, as described in FIGS. 2 and 3, the counter current reintroduction of heated solvent vapor into the vapor space prevents any appreciable amount of solvent vapor from flowing out of the machine with the cleaned items. In addition, since the evaporation of solvent occurs at temperatures well below the normal solvent boiling point at atmospheric pressures, the formation and transfer of any minute contaminated liquid droplets is minimized to the point of almostab'solute prevention. Operation of the vapor abstracting and con.- densing cycle during shut down can also prevent build-up of vapor pressure and leakage during that period. The utilization of both ends of the heat pumping cycle makes optimum use of all available energy which minimizes the power consumption and size and space requirements for the apparatus. This system isalso uniquely well adapted for automatic control because of its inherent balance of heat absorbed and discarded.

What is claimed is:

1. A method of removing foreign matter from a solvent fluid which comprises the steps of directing said fluid in heat exchange relationship with the heat emitting section of a heat pumping system to evaporate a portion of said fluid, collecting the unevaporated portion of said fluid, directing said evaporated portion of said fluid in heat exchange relationship with the heat absorbing section of said system for condensing it, and collecting the condensate which constitutes purified solvent.

2. A method as set forth in claim 1 wherein said collected unevaporated fluid solvent is returned to supply of fluid solvent to be purified.

3. A method for recovering fluid solvent vapor from the air and vapor mixture in the vapor space of a dry cleaning machine which comprises the steps of abstracting a portion of said mixture, cooling said abstracted portion by directing it in heat exchange relationship with the heat absorbing section of a heat pumping system to condense part of the fluid solvent vapor in said mixture, collecting said condensed fluid solvent, heating the uncondensed portion of said mixture by directing it in heat exchange relationship with the heat emitting section of said system to restore its solvent absorbing ability, and reintroducing said heated mixture back into said vapor space of said dry cleaning machine.

4. A method for recovering fluid solvent vapor from the air and vapor mixture in the vapor space of a dry cleaning machine which comprises the steps of abstract ing a portion of said mixture, cooling said abstracted portion to condense part of the fluid solvent vapor in said mixture, collecting said condensed fluid solvent, heating the uncondensed portion of said mixture to restore its solvent absorbing ability, reintroducing said heated mixture back into said vapor space of said dry cleaning machine, the material being treated in said dry cleaning machine being fed into an entrance and substantially continuously out of an exit from said vapor space, and said heated mixture being inwardly directed into said exit in a counterflow relationship to said material coming out of its to prevent the flow of solvent vapor out of said exit.

5. A method for recovering fluid solvent vapor from the air and vapor mixture in the vapor space of a dry cleaning machine which comprises the steps of abstracting a portion of said mixture, cooling said abstracted portion to condense part of the fluid solvent vapor in said mixture, collecting said condensed fluid solvent, heating the uncondensed portion of said mixture to restore its solvent absorbing ability, reintroducing said heated mixture back into said vapor space of said dry cleaning machine, said dry cleaning machine including a rinse tank holding clean solvent and a wash tank holding relatively dirty solvent, the condensed fluid being returned to said rinse tank to replenish the supply of clean solvent in it, and said rinse tank overflowing into said wash tank to purify the solvent in it.

6. A method as set forth in claim 5 wherein said dry cleaning machine is of the susbtantially continuously operating type, and said rinse tank overflowing into said Wash tank to provide a means for continuously purifying the solvent in said machine.

7. A method as set forth in claim 5 wherein said dry cleaning machine is intermittently. operated, a heat pump including heat absorbing and heat emitting sections being associated with said dry cleaning machine, said heat absorbing section being used for cooling said mixture, dirty solvent being sprayed over the heat emitting section of said heat pump, and the vapor evaporated by said heat emitting section also being condensed by said heat absorbing section for supplementing the replenishment of the supply of clean solvent for said machine.

8. A method as set forth in claim 7 wherein said dirty solvent is evaporated by said heat emitting section during any part of the dry cleaning process except the drying process.

9. An appartus for purifying dirty solvent fluid comprising a heat pumping system including heat emitting and heat absorbing elements, heat emitting and heat absorbing chambers respectively enclosing said elements, a pumpin system connected for spraying dirty solvent into said heat emitting chamber in heat exchange relationship with said heat emitting element whereby a portion of said solvent is evaporated, a dirty solvent drain from said heat emitting chamber for removing the unevaporated solvent, a vapor conduit connecting said chambers for conducting vapor into said heat absorbing chamber into heat exchange relationship with said heat absorbing element for condensing said solvent vapor, and a clean solvent drain from said heat absorbing chamber for removing said purified solvent from it.

10. An apparatus as set forth in claim 9 wherein said dirty solvent drain from said heat emitting chamber is connected to the dirty solvent storage tank from which said pumping system draws its supply.

11. An apparatus as set forth in claim 9 wherein said clean solvent drain pipe from said heat absorbing chamber is connected to a clean solvent storage tank.

12. An apparatus for recovering and purifying solvent being used in the operating chamber of a dry cleaning rnachine which encloses a vapor space containing a mixture of air and solvent vapor, said apparatus comprising a heat absorbing chamber having an entrance and an exit mounted adjacent said vapor space, an abstracting conduit connecting said vapor space with the entrance to heat absorbing chamber for conducting said mixture into said heat absorbing chamber whereby a portion of said vapor is condensed, a drain pipe from said heat absorbing chamber for removing the purified condensate formed therein, a passageway connecting said exit from said heat absorbing chamber to said vapor space, a heater in heat exchange relationship with said passageway for heating said mixture passing through it to restore its solvent absorbing ability before it is reintroduced into said vapor space, a propelling means for forcing said vapor from said vapor space through said heat absorbing chamber and said heater back into said vapor space through said passageway and said heat absorbing chamber and said heater being respectively provided by the heat absorbing and heat emitting element of a heat pumping system.

13. An apparatus as set forth in claim 12 wherein said dry cleaning machine is of the continuously operated type having an entrance and an exit through which items are introduced and removed from said operating chamber, and said passageway being directed inwardly into said exit to prevent vapor from flowing out of said vapor space with said cleaned items passing out through said exit.

14. An apparatus as set forth in claim 13 wherein a bulkhead divides said vapor space into a washing vapor space and a drying vapor space, an open solvent surface contiguous to said washing vapor space, said vapor abstracting conduit being connected to said washing vapor space, and a connecting conduit connecting said vapor spaces to each other for permitting relatively dryer vapor from said drying space to enter into said washing vapor space for replacing the vapor abstracted from it.

15. An apparatus as set forth in caim 12 wherein a rinse solvent storage tank is provided for storing purified solvent, and said drain pipe from said heat absorbing 10 chamber discharges into said rinse tank for replenishin its supply.

16. An apparatus as set forth in claim 15 wherein said rinse tank is mounted adjacent a supply of wash solvent, and an overflow means directs clean solvent overflowing from said rinse storage tank into said wash solvent supply for replenishing it.

17. An apparatus as set forth in claim 16 wherein the contacting area between said items and said wash solvent tank is appreciably greater than the contacting area between said items and said rinse solvent tank to cause the solvent vapor evolved from said items into said vapor space to primarily come from said wash solvent tank.

18. An apparatus as set forth in claim 12 wherein said dry cleaning machine is of the intermittently operated type in which solvent is periodically pumped into and drained out of said operating chamber, relatively dirty solvent being stored in a washing solvent tank and pure solvent being stored in a rinsing solvent tank, a pumping system connected said washing solvent tank with said casing of said machine and with said heat emitting chamber, a drain line from said heat, emitting chamber into said washing solvent tank for returning unevaporated washing solvent to said washing solvent tank, said heat emitting chamber enclosing a heating element for evaporating a portion of said washing solvent directed into it, a pure solvent drain line from said heat absorbing chamber to said rinsing solvent tank, and control means for directing washing solvent into said heat emitting chamber during phases of operation of said machine other than the drying cycle for replenishing the supply of rinsing solvent as said machine is being operated.

19. An apparatus as set forth in claim 18 wherein a conduit connects said heat absorbing chamber with the operating chamber of said machine for drawing vapor from said operating chamber into said heat absorbing chamber during the drying process for recovering solvent in the drying atmosphere and minimizing any pressure build up within said operating chamber during said drymg process.

20. An apparatus as set forth in claim 19 wherein said conduit comprises an inverted U-shaped tube having an open lower end which extends below the level of washing solvent and an orifice at its upper end for allowing vapor from said space to flow into said heat absorbing chamber when its pressure exceeds that in said heat absorbing chamber during washing and rinsing processes.

21. An apparatus as set forth in claim 18 wherein the vapor evaporating and condensing capacities of said heat emitting and heat absorbing chambers is suflicient to replenish the amount of purified solvent utilized in each rinsing operation, and said operating chamber includes a drain into said washing solvent tank to allow the solvent introduced into said operating chamber in said rinsing operation to replenish the amount of washing solvent drawn from said washing solvent tank.

References Cited in the file of this patent UNITED STATES PATENTS 2,310,569 Booth Feb. 9, 1943 2,720,083 Garland Oct. 11, 1955 3,002,287 Smith Oct. 3, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 070 463 December 25 1962 Donald Jo Bardy It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 25 for "'machnie read machine line 34L for "contact" read content -g co1umn.5,, line 73 for "52b" read 523 ---g column 6 line 51 after "loss" insert of column 7 line 43 for "buildup" read build-up column 8 line 38 for 'its read it =o Signed and sealed this 18th day of June 1963,

(SEAL) Attest:

DAVID L. LADD ERNEST w. VSWIDER "Commissioner of Patents Attesting Officer 

1. A METHOD OF REMOVING FOREIGN MATTER FROM A SOLVENT FLUID COMPRISES THE STEPS OF DIRECTING SAID FLUID IN HEAT EXCHANGE RELATIONSHIP WITH THE HEAT EMITTING SECTION OF A HEAT PUMPING SYSTEM TO EVAPORATE A PORTION OF SAID FLUID, COLLECTING THE UNEVAPORATED PORTIONS OF SAID FLUID, DIRECTING SAID EVAPORATED PORTION OF SAID FLUID IN HEAT EXCHANGE RELATIONSHIP WITH THE HEAT ABSORBING SECTION OF SAID SYSTEM FOR CONDENSI G IT, AND COLLECTING IN CONDENSATE WHICH CONSTITES PURIFIED SOLVENT 